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Abstract

In vitro fertilization‑embryo transfer (IVF‑ET) can be used by infertile couples to assist with reproduction; however, failure of the embryo to implant into the endometrial lining results in failure of the IVF treatment. The present study investigated the expression of chemokine receptor 7 (CCR7)(lo) programmed death‑1(PD‑1)(hi) chemokine receptor type 5 (CXCR5)+ cluster of differentiation 4 (CD4)+ T cells and associated factors in patients with repeated implantation failure (RIF). A total of 30 females with RIF and 30 healthy females were enrolled in the current study. Flow cytometry was used to detect the proportion of CCR7(lo)PD‑1(hi) CXCR5+ CD4+ T cells in the peripheral blood. Cytokine bead arrays were performed to detect the levels of interleukin (IL)‑6, ‑4 and ‑2 in the serum. ELISAs were used to detect the level of IL‑21 in the serum. Quantitative real time polymerase chain reaction analysis and immunohistochemistry were used to investigate the expression of B‑cell lymphoma 6 (Bcl‑6), chemokine receptor type 5 (CXCR5) and IL‑21 in the endometrium. The results revealed that the percentage of CCR7(lo)PD‑1(hi) CXCR5+ CD4+ T cells was increased in the RIF group compared with the control group during the mid luteal phase. The mRNA and protein levels of Bcl‑6, IL‑21 and CXCR5 in the endometrium and the concentrations of IL‑21 and IL‑6 in the serum were significantly increased in the RIF group; however, no significant difference was observed between the two groups in regards to the expression of IL‑4 and IL‑2. Furthermore, a significant positive correlation was identified between the percentage of CCR7(lo)PD‑1(hi) CXCR5+ CD4+ T cells and IL‑21 and IL‑6 levels. The expression of IL‑21 also had a positive correlation with Bcl‑6 and CXCR5 expression in the RIF group. These results suggest that increased levels of CCR7(lo)PD‑1(hi) CXCR5+ CD4+ T cells and associated factors contribute to RIF and could therefore be a potential therapeutic target.